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stewartI've got a 79 528i L-jet w/ a 4 speed I'm looking to swap w/ a 745 turbo motor. A bloke 'round here has 2 for sale. The cheaper, nonrunner has a blown gearbox but is an 84, ie motronic. The runner is an 81 l-jet but would cost twice as much. Would the motronic conversion be overly difficult? Any help would be immensely appreciated. thnx
Afshin-SwitzerlandSome people have done it before .... So it's not impossible. Actually everything is possible, its just a matter of how much time and money you want to spend on your project. If I had to give you an advise, I would tell you to go for the L-jet one. It's more expensive to buy, but you'll be alot more pleased with the results and save alot of time. The L-Jet one is a straight bolt on, and because of its OEM fited by-pass valve, does, work perfect with a manual shifter tranny (the Motronic one hasn't got it). If you decide to go Motronic, it would be alot easier to get the whole thing, I mean the engine and its 4HP22 tranny. The Motronic brain for engine works as a unit with this tranny, like retarding the ignition's timing at each shifting to get smoother gear changing ... etc. I think it's not worth the hassle to adapt it to your stick 4-speed. Just a L-Jet man's 02.... Regards, Afshin. 1982 745i
scottieI think the bottom line here is that you will be pushing new ground. I don't know of anyone that has installed this combo into an e12. I think the block will mount up without any problems except the right motor mount which will need to be fabricated. However I don't know about mounting the transmission. It seems as though if you are going to go through the hassle of adapting the turbo to run with a manual tranny, you might as well use a Getrag 265 5 speed instead of the 4 speed. I don't think you will have any problems with the lack of a blowoff valve unless you plan to run high boost. Scottie Sharpe San Jose CA Discussion Board SYSOP 84 745i 85 535i
stewartBack on the firstfives.org board it's been described as almost a bolt in, their main concern was the motronic conversion issue w/ the autobox. It's been described as the second most common swap for the e12. Second to dropping in the 3.3/3.5l motors. Its my understanding that the motor mounts are the same for the 2.5/2.8, 3.3/3.5 and the mounts for the turbo motor too. I may have incorrect info but that's what I'd heard thnx
scottieOh, that's good news and great information. I had a 77 530 that had a callaway turbo on it. I had to put a 2.9 final in it because it generated too much torque. It is true that the electronic version of the HP4 transmisison does talk to the motronic, but I have seen five-speed conversions of 745's and they do work. I think you could get away with disconnecting the tranmission feedback. The engine should run fine. But I am only guessing here. Jens would probably have good advice concerning this issue. In any case, this sounds like a great project. One this is for sure, 745i's are going to get rarer as they become donor cars for turbo projects!! Scottie Sharpe San Jose CA Discussion Board SYSOP 84 745i 85 535i
Afshin-Switzerland
quote:
you might as well use a Getrag 265 5 speed instead of the 4 speed. I don't think you will have any problems with the lack of a blowoff valve unless you plan to run high boost. Scottie Sharpe San Jose CA Discussion Board SYSOP 84 745i 85 535i
Scottie ! I have to disagree with you ... If he does, drop the auto tranny for a stick, higher boost levels or not, a by-pass valve IS important. That would keep your turbo spooling while you're shifting. No by-pass valve = going almost out of boost at each shifting ! Regards, Afshin. 1982 745i
M545iremember the e12 is lighter than the e23 and even when going out of boost will not mean you don't have power anymore. L-jet is the easiest conversion, but get a 5 speed, they are cheap no? Don't know for the e12 but e28 needs custom exhaust side motor mount. Motronic is possible with 5speed but I never did it and I only heard that the car ran good without tranny ECU. But this doesn't mean that the engine is running safe, I just don't know. Good luck, you will see once finished you will be a lucky man M545i